1. Field of the Invention
This invention relates to a motor vehicle door locking system having a piezoelement, and a process for controlling a motor vehicle door locking system.
2. Description of Related Art
European patent application EP 1 103 432 A1 discloses a motor vehicle door locking system in which a piezoelement is used as a sensor element, the piezoelement being installed in a substantially rigid outside door handle of the motor vehicle. The piezoelement is used to detect actuation of the outside door handle by an operator. In the disclosed motor vehicle door lock, there exists a disadvantage in that when the piezoelement fails, complex troubleshooting is required and the operating safety of the motor vehicle may also be compromised.
The international application WO 99/28170 discloses a motor vehicle door locking system in which pulling an outside door handle initiates the starting interval of data interrogation of a so-called “passive entry” function in order to ascertain whether the operator who is actuating the outside door handle is authorized for access. Pulling of the outside door handle can be detected, among others, by deformation of the piezoelement. Here, it is also disadvantageous if the piezoelement which is assigned to the outside door handle fails. This requires complex troubleshooting since failure would be assumed to be primarily in the “passive entry” function. It is furthermore disadvantageous if continuous evaluation or monitoring of the signals of the piezoelement is required in order to be able to start data interrogation directly after actuation of the outside door handle.